Hello Guys,

     Although it's a little too large to qualify as an Ultralight radio, the ICF-SW7600GR provides fairly competent MW performance in a compact, SSB-capable design.  For those MW DXers unable to accommodate an ICF-2010 for space or financial reasons, this Sony portable would be perfect as an SSB "spotting receiver" for Ultralight radio transoceanic targets on an ocean beach...  if only it had more sensitivity.  Having had an unused unit sitting around since the Ultralight "Boom" started late last year (and faced with a situation where a multi-family vacation would make packing space extremely limited), there was a sudden compulsion to replace the stock 4.75" x .37" loopstick with a much more effective Amidon 7.5" x .5" loopstick wound with 40/44 Litz wire.  This MW frequency-optimized combination has provided an incredible sensitivity increase in the SRF-39FP and Eton E100 Ultralight models (enabling both to receive Australia signals at Grayland), and I was curious how far it would boost the performance of this compact SSB portable.

     The ICF-SW7600GR has a stock loopstick very similar to that of the ICF-2010, in which a fixed larger center coil is mated with a much smaller tickler coil, used for adjustment of the unit's spurious signal rejection.  As such, the instructions for "supercharging" the ICF-2010 (currently posted in dxer.ca's Ultralight File section) are electrically applicable to the ICF-SW7600GR, although the lsmaller unit has a large coil inductance of 983 mh, and the stock loopstick does not have a snap-out design like the 2010, requiring the hobbyist to use a moderate amount of effort in separating the glue at the base of the ferrite bar.

     The performance improvement for this $30 modification has certainly exceeded expectations!  When the stock unit was checked against a stock ICF-2010 prior to modification, it was clearly inferior in sensitivity on all frequencies.  The stock 2010 was far more effective in digging out weak daytime fringe stations, with or without the Synch function.  After the ICF-SW7600GR received the Amidon 7.5" loopstick, the situation was completely reversed.  The still-compact SW7600GR now clearly outperforms the stock 2010 on all MW frequencies--  low, middle and high band.  High-band performance is particularly striking, with Synch lock performance on a 1610 TIS station completely inaudible on the stock 2010.  This has been achieved despite a very modest expenditure for parts (about $20 for the Amidon ferrite bar, and under $10 for the Litz wire and other items).  The modified SW7600GR is also much smal ler and lighter than a stock 2010, providing a very practical, compact SSB "spotting receiver" for Ultralight TP/TA chasers.

     Two pictures of this modified ICF-SW7600GR have been uploaded to the "ultralightdx" Yahoo Group site, in the "Roll Your Own DXing Monster" album.  It is hoped that various MW DXers will feel motivated to modify their own ICF-SW7600GR units, and obtain the outstanding MW performance possible with this model.

                         73,  Gary DeBock

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My Eton E-100 from "The Shortwave Store" in Canada arrived,
safe and sound, this past Saturday! Even after reading the
reviews of the radio and seeing pictures of it on various
websites, I was still amazed at just how small the radio
really is. Sure fits the description of an "ultralight!"

Not a bad price, either! Less than half the list price,
thanks to a special from Gary DeBock of www.dxer.ca.

One minor problem, though - the 2 AA batteries that came
with the radio (Eton brand) had started to corrode. But,
thankfully, they were still in the shrink-wrap and didn't
damage anything inside the box. AND, there were 2 new
AA alkaline batteries taped to the outside of the box, so
I came out okay!

Haven't had any time to do anything with the radio other
than to put the new batteries in, set the time, and check
out the controls to see if they work.

I'm hoping to have some time later this week to test the
radio, do some bandscans, etc. We'll see.

73 & Great DX!

Steve N5WBI
Houston TX

I notice that both my digital SANGEAN PR-D5 and my analog SONY ICF-S5W and
EX5 all can be tuned to a given frequency, and then used to boost a signal
significantly on an ultralight tuned to the same frequency. My question
is, why do the analogs work as a booster even when off while the digital
works as a booster only when turned on?

Hello Guys,
 
     Some DXers have inquired about the recent success in modifying the Eton E100 and other Ultralights for DXpedition use, so here is a brief summary of the current progress.
 
SRF-39FP:  This analog model has had various modifications for improved tuning dials, digital readout, monster loopsticks and other changes, but the basic limitation of all these efforts is that without the availability of a commercial upgraded IF filter to improve selectivity, this model cannot receive the 9 kHz splits without the lucky combination of a strong DX signal and little (or no) domestic QRM.  The bizarre 50 kHz IF has been a real roadblock for selectivity mods, and without such a mod, the DXpedition potential of all the SRF-39FP (and SRF-59) models is greatly limited.  The recent Amidon 7.5" loopstick model, however, shows great promise for domestic DX use because of its extreme sensitivity, and for general TP chasing during which its superior nulling ability can be used, it may prove effective in chasing Asian TP's in the northwest, during the upcoming fall season.  One of these models recently received 5AN-891 in Australia, but this was only because of the total lack of domestic QRM on the frequency.
 
DT-200VX:  This digital model has had both transplanted loopsticks and 450 kHz selectivity mods, but not yet in combination.  Some efforts were made to replace the stock loopstick with 6.25" vintage ferrite-bar models, but the lack of broadband sensitivity in the digital design hampered the efforts (this was also an initial problem in the E100 modification efforts, until the development of the "sliding coil" loopstick).  To my knowledge, all modification efforts were suspended in the spring, in favor of the SRF-39FP and E100 models.  Since there has been great modification success with the E100 digital model since then, the DT-200VX, another digital design with similar performance,  could also presumably be greatly transformed by the application of upgraded IF filters and a large sliding-coil loopstick.
 
E100:   This model has undoubtedly become the major DXpedition breakthrough we were hoping for.  With its 1 kHz tuning ability, 200 memories and 455 kHz IF, its circuitry seems almost perfectly designed for modification into a DXpedition superstar.  John Bryant had great DX success in modifying his unit to receive signals from external antennas, such as his superb Wellbrook 4-element Array at Grayland.  But even as a stand-alone portable, recent developments have combined to make the E100 an extremely effective DX chaser.  The first big breakthrough was the development of the "sliding coil" loopstick, which overcomes the E100's lack of broadband (530-1700 kHz) sensitivity.  An offshoot of the alignment process, the "slider" loopstick simply allows the user to peak the loopstick coil on each received signal, instead of securing it at the 600 kHz peak position.  Although this concept can be used with any E100 (even stock models), when the mediocre E100 stock loopstick is replaced with a huge Amidon or Stormwise ferrite bar-based loopstick, the application of the "slider" concept provides an incredible increase in sensitivity, boosting the E100 well past the level of any stock portable on the planet.
     Another huge improvement was Guy Atkins' suggestion of a Murata CFJ455K5 premium IF ceramic filter, to replace the stock filter.  The CFJ455K5 is the same premium IF filer as used in the Eton E1, and it has similar performance in the E100.  It cuts through domestic QRM very effectively, and in combination with the larger "slider" loopsticks, the narrow IF filter makes split-frequency DX chasing a breeze.  Prior to development of the modified E100's, nobody on the west coast had been able to receive any type of DU signal with any type of modified Ultralight.  Now, with three hard-core Washington state DXers using modified E00's, all three of us have logged multiple DU's with ease.. and we can't wait for more  :>)
 
73,  Gary DeBock
 
 
                                                                 

I've run up against the need to reduce the length of the
stock ferrite bar by half.

Has anybody ever done this successfully??? Have you ever heard rumors
of someone doing this successfully? HOW????